Field of the Invention
The invention pertains to the field of the use of environmentally destructive or otherwise undesirable waste fumes, gasses and streams for economically constructive purposes. More specifically, the invention pertains to the use of such waste fumes, gasses and streams in the production of graphene, graphene derivatives and other nanoparticles.
Description of Related Art
There are currently methods known to the art for producing graphene and other useful graphitic nanoparticles through the use of both solid carbon dioxide (“dry ice”) and gaseous carbon dioxide (CO2), (see, for example in the first case, Chakrabati et al., “Conversion of carbon dioxide to few-layer graphene,” J. Mater. Chem., Vol. 21, pp. 9491-9493, 2011; Jeon et al., “Edge-carboxylated graphene nanosheets via ball milling,” Proc. of the Nat. Acad. of Sci., Vol. 109, No. 15, pp. 5588-5593, 2012; and in the second case, U.S. Pat. No. 8,420,042, entitled “Process for the production of carbon graphenes and other nanomaterials” by Dickenson et al., Apr. 16, 2013). Those methods employing gaseous CO2 as a substrate aspire to use potentially environmentally harmful industrial emissions of CO2 as the feedstock, thereby helping to reduce greenhouse gas emissions into the atmosphere. Although well-intentioned, these methods currently known to the art either employ expensive reactants or use potentially dangerous catalyst materials (such as violently reactive elemental earth metals), but all produce end-products themselves of little commercial value. In the case of U.S. Pat. No. 8,420,042 supra, the reduction of CO2 is accomplished using highly reactive and unstable elemental magnesium. These current efforts at chemical reduction of CO2 to useful precursor materials are also universally marred by significant economic challenges.
Other troublesome so-called greenhouses gasses include methane, ethane and propane. Copious amounts of methane-related gasses are released into the atmosphere as a result of natural gas exploration, drilling, extraction and processing; most notably from the process of induced hydraulic fracturing (a/k/a “hydrofracking” or more commonly “fracking”), see Jeff Tollefson, “Air sampling reveals high emissions from gas field,” Nature, 482, pp. 139-140, 2012; Mark Fischetti, “Fracking Would Emit Large Quantities of Greenhouse Gasses,” Scientific American, Jan. 20, 2012. It is also known that both methane and ethane can be used as a starting material in the production of graphene. See Wassei et al., “Chemical Vapor Deposition of Graphene on Copper from Methane, Ethane and Propane: Evidence of Bilayer Selectivity,” Small, vol. 8, issue 9, pp. 1415-1422, 2012.
Although there are many carbon dioxide sequestration/utilization methods known to the art, such as those described in: Hydrogenation of CO2 to synthetic methanol (see Wesselbaum, et al., “Hydrogenation of Carbon Dioxide to Methanol by Using a Homogeneous Ruthenium-Phosphate Catalyst,” Angewante Chemie, Vol. 51, Issue 30, pp. 7499-7502, 2012, Yang et al., “Fundamental studies of methanol synthesis from CO2 hydrogenation on Cu(111), Cu clusters, and Cu/ZnO(0001),” Phys. Chem. Chem. Phys., Vol. 12, pp. 9909-9917, 2010, and Meyer Steinberg, Brookhaven National Lab Report Number 63316: The Carnol Process System for CO2 Mitigation and Methanol Production, Department of Advanced Technology, Brookhaven National Laboratory, Upton, N.Y.; M. Steinberg, “The Carnol Process for CO2 Mitigation and Methanol Production,” Energy, Vol. 22, Issues 2-3, pp. 143-149, 1997; M. Hallmann and M. Steinberg, Greenhouse Gas Carbon Dioxide Mitigation: Science and Technology, CRC Press, LLC, Boca Raton, Fla., 1999; C. Creutz and E. Fujita, Carbon Management: Implications for R&D in the Chemical Sciences and Technology: A Workshop Report to the Chemical Sciences Roundtable, National Academies Press, Washington, D.C., 2001); Conversion of CO2 to methanol via specialized algae; Conversion of CO2 to methanol via enzymes; Solar conversion of CO2 to methanol; Conversion of CO2 to salicylic acid (see T. Lijima and T. Yamaguchi, “K2CO3-Catalyzed direct synthesis of salicylic acid from phenol and supercritical CO2,” Applied Catalysis A: General, Vol. 345, Issue 1, pp. 12-17, 2008); Conversion of CO2 to ethylene carbonate (see, North et al., “A Gas-Phase Flow Reactor for Ethylene Carbonate Synthesis from Waste Carbon Dioxide,” Chemistry—A European Journal, Vol. 15, Issue 43, pp. 11454-11347, 2009), etc, widespread implementation of all of these methods is marred by a financial hurdle owing to the low economic value of the most common end-product—synthetic methanol—an otherwise abundant and cheap material.
Besides traditional CO2 emissions from smokestacks, there are many other potentially harmful environmental releases of carbonaceous gasses or hydrocarbon-laden waste water from processes such as concrete asphalting, roof tarring, oil well drilling, natural gas well drilling, natural gas processing, torrefaction of biomass, gassification of coal, wood gassification and virtually any process involving the complete or partial hydrothermal carbonization of carbonaceous material.
Carbonaceous waste streams are also created when materials such as shale gas, tight gas, tight oil, and coal seam gas are extracted from the earth during fracking in which water and chemical additives are pumped into a geologic formation at high pressure. When the pressure exceeds the rock strength, the fluids open fractures and a propping agent is pumped into the fractures to keep them from closing when the pumping pressure is released. The internal pressure created within the geologic formation causes the injected fracturing fluids to rise to the surface where it can be recovered and stored in tanks or pits. Currently, flowback is typically discharged into surface water or injected underground. VOCs believed to be released as a result of fracking and natural gas processing are reported to include the following, all of which are believed to be excellent feedstock for graphene production using the invention:
1,2-Cyclohexane Dicarboxylic AcidDiisononyl Ester (Hexamoll ® DINCH ®)1,2,4-Trimethylbenzene1,3,5 Trimethylbenzene2-methyl-4-isothiazolin-3-one5-chloro-2-methyl-4-isothiazotin-3-oneAromatic HydrocarbonAromatic KetonesDazometDieselDi-2-ethylhexyl Phthalate (DEHP)DiethylbenzeneDiisodecyl Phthalate (DIDP)Diisononyl Phthalate (DINP)Doclecylbenzene Sulfonic AcidEthoxylated OctylphenolEthylbenzeneKeroseneNaphthaleneOil MistPetroleum Distillate BlendPetroleum DistillatesPetroleum NaphthaPolysaccharidePropargyl AlcoholSucroseTolueneXyleneSee, e.g., Chemicals Used by Hydraulic Fracturing Companies in Pennsylvania For Surface and Hydraulic Fracturing Activities, prepared by the U.S. Department of Environmental Protection, Bureau of Oil and Gas Management, Washington D.C., Jun. 30, 2010.
It is believed that many, if not all, of these aforementioned processes create waste vapors and streams that already contain some quantity of recoverable and useful graphene, graphene derivatives (such as graphene oxide) or polycyclic aromatic hydrocarbons (PAHs) that may be used (collected) without further processing, or may require minimal processing, to produce a commercially-viable product stream.
The Related Applications disclose economical dehydration reactions and/or reflux pyrolysis methods to form graphitic carbon from a carbonaceous material carbon source. The disclosed reactions and methods subject carbonaceous materials to reflux pyrolysis, oxidation/reduction, incomplete combustion or acid dehydration to form graphitic carbon reactant starting materials wherein, following refluxing, graphene/graphene oxide (GO) is emitted as nanoscopic scales or “nanoscales” suspended in a vapor/steam. The resulting graphene/GO scales can travel in the vapor and be collected either by direct deposition onto a solid substrate in physical contact with the emitted vapor, or by applying the particle-containing vapor to an aqueous solution or liquid used to promote “hydrophobic self-assembly” of the scales into larger graphene/GO sheets. In one embodiment, the reaction environment is controlled to limit the amount of ambient oxygen (O2) in the chamber, discouraging complete combustion of the reactants during heating. In one embodiment, the reaction is carried out in the presence of an added solvent. In one embodiment, the produced GO is converted to reduced graphene oxide (rGO) or graphene sheets suspended in a heated or unheated liquid collection medium.
As disclosed in the Related Applications, the carbonaceous starting material may be subjected to a dehydration reaction or pyrolysis to form graphitic carbon, and/or the carbonaceous starting material may be in whole or in part graphitic.